I'm thinking of using a prong collar for my female german shepherd but have heard so many bad things about them. also a lot of good results. i had talked to my friends dog trainer and he recommended me using a medium sized prong collar. before i go ahead on buying one i need some opinions on wether i should or not. my shepherd does Great off leash but city rules say i must have her on leash. and she pulls excessively when on one. I've tried using gentle leader but still doesn't seem to quiet work. she's been on one for a couple months but always seems to chew them apart and just keep pulling.